The twin-twin transfusion syndrome: spectrum of cardiovascular abnormality and development of a cardiovascular score to assess severity of disease

Type IV intestinal atresia, congenital bilateral perisylvian syndrome, and chronic pulmonary hypertension secondary to multiple vascular disruption syndrome in a monochorionic twin

We describe a rare case of multiple intestinal atresias, congenital bilateral perisylvian polymicrogyria, and chronic pulmonary hypertension in a surviving monochorionic twin with co-twin demise. This constellation of congenital anomalies represents a multiple vascular disruption syndrome due to intrauterine vascular compromise in the setting of possible twin-to-twin transfusion syndrome.

Assessment of right ventricular function in recipient twin of twin to twin transfusion syndrome with speckle tracking echocardiography

This study was undertaken to evaluate the right ventricular myocardial systolic function and its relation to the fetal volume and pressure overload in recipient twin of twin to twin transfusion syndrome with speckle tracking echocardiography. Longitudinal peak systolic strains of the right ventricle were measured by speckle tracking echocardiography in 17 patients with twin-to-twin transfusion syndrome (TTTS) and 19 normal monochorionic diamniotic pregnancies. The right ventricular free wall thickness in recipient twin (0.43 ± 0.14 cm) was significantly larger than that in the donor (0.21 ± 0.04 cm, p < 0.05) and the control group (0.18 ± 0.03 cm, p < 0.05 for larger twin and 0.17 ± 0.02 cm, p < 0.05 for smaller twin). Although there were no significant differences in the right ventricular fractional shortening and cavity area percent change among control and the TTTS groups, the absolute value of peak systolic strains of ventricular septum, right ventricular free wall and global right ventricle in recipients were all significantly lower than those of the donors and the control group. Besides, the global right ventricular peak systolic strain correlated well with gestational age adjusted right ventricular free wall thickness (r = 0.65, p = 0.04) but not with gestational age adjusted right ventricular end-diastolic dimension (r = 0.38, p = 0.28) and cavity area percent change (r = 0.33, p = 0.35). Right ventricular systolic dysfunction measured with decreased right ventricular peak systolic longitudinal strain exists despite the absence of diminished fractional shortening and cavity area percent change and this reduced systolic function correlates with the right ventricular pressure overload as shown by increased right ventricular free wall thickness.

Twin-twin transfusion syndrome

Twin-twin transfusion syndrome (TTTS) is a serious condition that affects 10% to 15% of twin pregnancies with monochorionic diamniotic placentation. The pathophysiology of TTTS is not completely understood; however, the presence of unbalanced placental vascular communications within a shared circulation has been implicated in its development. The presentation of TTTS is highly variable, and it does not always progress in a predictable manner. Monochorionic twin gestations should, therefore, be monitored for signs of TTTS with serial sonograms starting in the second trimester. Early TTTS can be managed conservatively. However, without intervention, early-onset advanced TTTS is associated with a high perinatal loss rate and risk of severe neurologic impairment among survivors. Limited studies suggest that fetoscopic laser photocoagulation is the best available treatment for advanced TTTS diagnosed in the second trimester. Even with laser therapy, there remains a significant risk of twin demise and neurologic handicap in survivors.

Evaluation of conventional Doppler fetal cardiac function parameters: E/A ratios, outflow tracts, and myocardial performance index

Structural evaluation of the fetal heart is well established. Functional evaluation using pulsed-wave Doppler may also be performed. E/A ratios express the relationship between the maximal velocities of the E and A waveforms of ventricular filling. In normal fetuses, E/A ratios are usually <1 but show a constant increment during gestation, mainly related to the increment of the E wave. In intrauterine growth restriction (IUGR) fetuses, E/A ratios are lower compared to values in normally grown fetuses at the same gestational age. Cardiac outflows provide information on the time-velocity integral that, combined with the vessel area, allows calculation of the left and right cardiac outputs. In normal fetuses there is a predominance of the right ventricle (55-60%) in contributing to the combined cardiac output. In IUGR fetuses this predominance shifts to the left ventricle in order to increase the flow to the upper part of the fetal body and brain. The myocardial performance index (MPI) also provides information on systolic and diastolic cardiac function. The MPI is an early and consistent marker of cardiac dysfunction which becomes altered in early stages of chronic hypoxia or in cases with cardiac overload such as in twin-to-twin transfusion syndrome.

Fetal cardiac function: technical considerations and potential research and clinical applications

Fetal echocardiography was initially used to detect structural anomalies but has more recently also been proposed to assess fetal cardiac function. This review summarizes technical issues and limitations in fetal cardiac function evaluation, as well as its potential research and clinical applications. Functional echocardiography has been demonstrated to select high-risk populations and to be associated with outcome in several fetal conditions including intrauterine growth restriction, twin-to-twin transfusion syndrome, maternal diabetes, and congenital diaphragmatic hernia. Fetal heart evaluation is challenging due to the smallness and high heart rate of the fetus and restricted access to the fetus far from the transducer. Due to these limitations and differences in cardiac function which are related to fetal maturation, cardiovascular parameters should be validated in the fetus and used with caution. Despite these precautions, in expert hands and with appropriate ultrasound equipment, evaluation of cardiac function is feasible in most fetuses. Functional fetal echocardiography is a promising tool that may soon be incorporated into clinical practice. Research is warranted to further refine the contribution of fetal cardiac assessment to the diagnosis, monitoring, or prediction of outcomes in various fetal conditions.

Maternal-fetal surgery for structural malformations

Although most prenatally diagnosed correctable anatomic abnormalities are best addressed by surgical interventions after birth, the outcomes of a small number of severe structural malformations with predicted fetal demise or devastating sequelae postnatally may be improved by correction before birth. Consideration of maternal-fetal surgical intervention is restricted to those anatomic malformations that interfere with normal organ development and which, if alleviated, may permit normal development to proceed. Advances in prenatal diagnosis and technical innovations in the surgical approach to the fetus have resulted in an increase in the successful clinical application of fetal intervention over the past 3 decades. The purpose of this review is to describe the current status of maternal-fetal surgery, with a focus on the congenital anomalies most commonly treated by intervention before birth, and to highlight the key areas for further research in this evolving surgical specialty.

Functional assessment of the fetal heart: a review

The purpose of this review is to evaluate the current modalities available for the assessment of fetal cardiac function. The unique anatomy and physiology of the fetal circulation are described, with reference to the difference between in-utero and ex-utero life. M-mode, early/atrial ratio, myocardial performance index, three-dimensional and four-dimensional ultrasound, tissue Doppler including strain and strain rate, speckle tracking, magnetic resonance imaging and venous flow assessment are described. The modalities are analyzed from the perspective of the clinician and certain questions are posed. Does the modality assess systolic function, diastolic function or both? Is it applicable to both ventricles? Does it require extensive post-processing or additional hardware, or does it make use of technology already available to the average practitioner? The reproducibility and reliability of the techniques are evaluated, with reference to their utility in clinical decision-making. Finally, directions for future research are proposed.

Prevalence and progression of recipient-twin cardiomyopathy in early-stage twin-twin transfusion syndrome

OBJECTIVE

The management of twin-twin transfusion syndrome (TTTS) in its early stages (Quintero Stages I and II) is controversial. We describe the prevalence, severity, incidence and rate of progression of recipient-twin cardiomyopathy in Stages I and II TTTS.

METHODS

Among 451 cases of TTTS evaluated between 2004 and 2009, 123 (27.3%) cases of Stages I and II were reviewed. Echocardiography was used to 'upstage' cases based on the presence or absence of mild (IIIA), moderate (IIIB), or severe (IIIC) recipient cardiomyopathy. Progression was defined by worsening in the degree of recipient-twin cardiomyopathy from initial presentation or failure to respond to amnioreduction. Outcome data included progression of recipient-twin cardiomyopathy, treatment and survival to birth. Data were compared by the chi-square, Fisher's exact test or t-test as appropriate.

RESULTS

Seventy-seven of 123 (62.6%) cases were Quintero Stage I and 46/123 (37.4%) Quintero Stage II. Eighty (65.0%) were upstaged to Cincinnati Stage IIIA (n = 25), IIIB (n = 23) or IIIC (n = 32). Management included observation in 11 (8.9%), amnioreduction in 26 (21.1%), amnioreduction followed by selective fetoscopic laser photocoagulation (SFLP) in 43 (35.0%) and primary SFLP in 43 (35.0%). Of 80 cases managed by observation or amnioreduction initially, 43 (53.8%) progressed within a mean duration of 1.4 ± 1.5 weeks. The incidence of progression increased significantly as degree of recipient-twin cardiomyopathy at presentation worsened: Stage I, 9/27 (33.3%); Stage II, 8/15 (53.3%); Stage IIIA, 8/16 (50.0%); Stage IIIB, 10/10 (100%); and Stage IIIC, 8/12 (66.7%) (χ(2) = 14, P < 0.01). Overall fetal survival was 205 out of 244 (84.0%). Fetal survival with observation only was 81.8% (18/22), with amnioreduction only it was 92.3% (48/52), with initial observation or amnioreduction followed by SFLP it was 86.9% (73/84) and with primary SFLP it was 76.7% (66/86).

CONCLUSION

Echocardiography demonstrates a high incidence of recipient-twin cardiomyopathy in early-stage TTTS. The more advanced the recipient-twin cardiomyopathy is, the more likely is progression to occur during observation or following amnioreduction.

Diastolic Cardiac Pathology and Clinical Twin-Twin Transfusion Syndrome in Monochorionic/Diamniotic Twins

OBJECTIVE: to identify differences in echocardiographic profiles of monochorionic/diamniotic pregnancies with early or mild twin-twin transfusion syndrome (TTTS), compared to monochorionic/diamniotic twins affected only by discordant growth or discordant fluid. STUDY DESIGN: retrospective evaluation of sonograms and echocardiograms of twin pregnancies referred for suspected TTTS. RESULTS: 112 monochorionic/diamniotic pairs were studied. 41 did not have/develop TTTS, 61 had Stage I/II TTTS. Ten developed TTTS after initially not meeting criteria. TTTS recipients had a higher rate of venous Doppler or tricuspid inflow abnormalities than purported "recipients" in non-TTTS pregnancies (86% vs. 37%, P<0.001). TTTS recipients had shorter tricuspid inflow duration/RR intervals than non-TTTS fetuses (32+/-6% versus 37+/-4%, P<0.001). Logistic regression and recursive partitioning identified shorter tricuspid inflow duration, longer isovolumic relaxation, and ductus venosus abnormality associated with TTTS. CONCLUSION: Diastolic pathology, specifically shorter tricuspid inflow duration, may be considered a hallmark of TTTS distinguishing these pregnancies from other monochorionic/diamniotic twin complications.

Laser therapy for twin-to-twin transfusion syndrome (TTTS)

Monochorionic twins are subjected to specific complications which originate in either imbalance or abnormality of the single placenta serving two twins including twin-to-twin transfusion syndrome. The diagnosis is well established in overt clinical forms with the association of polyuric polyhydramnios and oliguric oligohydramnios. The best treatment of cases presenting before 26 weeks of gestion is fetoscopic laser ablation of the intertwin anastomoses on the chorionic plate. Although subjected to subtle variations, the core technique follows robust guidelines which could help understanding and acquiring the required skills and experience to perform this procedure. However appropriate and tailored hands-on training and appropriate perinatal set-up are critical not only for surgical management but also for the follow-up and management of related complications.

Twin-to-twin transfusion syndrome (TTTS)

Twin-to-twin transfusion syndrome (TTTS) is a severe complication of monochorionic (MC) twin pregnancies, characterized by the development of unbalanced chronic blood transfer from one twin, defined as donor twin, to the other, defined as recipient, through placental anastomoses. If left untreated, TTTS is associated with very high perinatal mortality and morbidity rates, due to a combination of fetal and/or obstetric complications. The reported prevalence is 10-15% of all MC twins, or about 1 in 2000 pregnancies. This consensus document reviews available evidence and offers practical guidance to clinicians by providing recommendations on various aspects concerning diagnosis and management of TTTS.

New and/or improved aspects of fetal surgery

Open fetal surgery through a wide hysterotomy is no longer a real option for prenatal intervention, but a minimally invasive approach has emerged as treatment for a small number of indications. Endoscopic ablation of placental vessels is the preferred treatment for severe twin-to-twin transfusion syndrome and it may be the only chance to salvage the most severe forms of congenital diaphragmatic hernia. Several other indications are currently under review and may become justified in the future, provided that diagnostic accuracy and patient selection become more accurate. Before invasive fetal intervention becomes widely accepted, however, we need to better define outcome. It is no longer acceptable to express results in terms of survival at birth. Survival at discharge and long-term morbidity must be considered as well.

Techniques for assessing cardiac output and fetal cardiac function

Fetal echocardiography was initially used to diagnose structural heart disease, but recent interest has focused on functional assessment. Effects of extracardiac conditions on the cardiac function such as volume overload (in the recipient in twin-twin transfusion syndrome), a hyperdynamic circulation (arterio-venous malformation), cardiac compression (diaphragmatic hernia, lung tumours) and increased placental resistance (intrauterine growth restriction and placental insufficiency) can be studied by ultrasound and may guide decisions for intervention or delivery. A variety of functional tests can be used, but there is no single clinical standard. For some specific conditions, however, certain tests have shown diagnostic value.

Outcome prediction in monochorionic diamniotic twin pregnancies with moderately discordant amniotic fluid

OBJECTIVE

The aim of this study was to identify predictors of twin-to-twin transfusion syndrome (TTTS) and selective intrauterine growth restriction (sIUGR) in monochorionic diamniotic (MCDA) twin pregnancies with moderate amniotic fluid discordance (mAFD).

METHODS

Monochorionic twins with mAFD (n = 45; gestational age, 15-29 weeks) were assessed for extent of fluid discordance, fetal growth discordance and fetal cardiac dysfunction, and were followed longitudinally. A prediction algorithm was constructed for TTTS and sIUGR and validated in an unrelated cohort (n = 52).

RESULTS

Cardiac dysfunction could not predict TTTS or sIUGR. Twins below 20 weeks of gestation with a fluid discordance of ≥ 3.1 cm had a risk of TTTS of 85.7%. Sensitivity for TTTS was nevertheless only 55%. An intertwin weight discordance of ≥ 25% had 63% sensitivity and 76% specificity for sIUGR without TTTS.

CONCLUSION

The outcome of MCDA twins with mAFD remains unpredictable, yet high-risk and low-risk subgroups for TTTS can be identified based on severity of fluid discordance and gestational age.

Effect of selective fetoscopic laser photocoagulation therapy for twin-twin transfusion syndrome on pulmonary valve pathology in recipient twins

OBJECTIVE

To investigate the impact of selective fetoscopic laser photocoagulation (SFLP) on pre-existing pulmonary valve pathology in the recipient twin in twin-twin transfusion syndrome (TTTS).

METHODS

We evaluated preoperative echocardiograms of all pregnancies with TTTS treated with SFLP at our institution from 2001 to 2009 (n = 76). Sixteen (21%) recipients had an abnormal pulmonary valve (stenosis/dysplasia, insufficiency or functional atresia) before SFLP. Postoperative echocardiograms and medical records from these 16 recipients were reviewed. Changes in pulmonary valve structure and function, and overall cardiac function, were noted after SFLP.

RESULTS

The mean gestational age at SFLP was 21 (range, 18.7-24.3) weeks. Seven of sixteen (44%) recipients with abnormal pulmonary valve prior to SFLP survived. Six of the 16 (37.5%) recipient twins had documented absence of persistent pulmonary valve abnormalities at birth or at autopsy. Two (12.5%) of the 16 recipients (2.6% of the original cohort) had persistent pulmonary valve abnormalities at birth, requiring intervention. Systolic and diastolic function improved or normalized after SFLP in all patients undergoing longitudinal follow-up. There was a tendency for a better cardiovascular profile score (best = 10 points) at initial evaluation in pregnancies with survivors compared with those with no survivors (mean (SD): 5.6 (2.2) vs. 6.75 (1.28)), but this was not statistically significant. Severity of cardiac involvement did not predict persistence of valve pathology or survival.

CONCLUSIONS

SFLP can improve flow through the pulmonary valve of the recipient twin in TTTS, probably as a consequence of improvements in right ventricular systolic and diastolic function. However, pulmonary valve pathology may persist and require postnatal intervention.

Fetal cardiovascular effects of lower urinary tract obstruction with giant bladder

OBJECTIVE

Lower urinary tract obstruction (LUTO) with massive bladder distension impacts on a variety of developing organ systems with consequent morbidity and mortality. The impact of LUTO on the fetal cardiovascular system has not previously been investigated. We hypothesize that a giant, distended bladder within the pelvis may cause vascular compression with observable consequences.

METHODS

Fetal echocardiography was performed in 42 fetuses with LUTO and compared with 35 normal controls matched for gestational age. Parameters investigated included cardiothoracic ratio, presence or absence of ventricular hypertrophy and pericardial effusion. Doppler echocardiographic examination of mitral and tricuspid valve inflow and the ductus venosus was performed. To assess arterial vascular impedance, pulsatility indices (PIs) were calculated for segments of the descending aorta and right and left iliac arteries (RIA and LIA).

RESULTS

In the LUTO group an increased cardiothoracic ratio was seen in nine (21%), ventricular hypertrophy in 12 (29%) and small pericardial effusion in 15 (36%). Filling characteristics of the right ventricle in the LUTO group demonstrated greater dependency upon atrial contraction, and ductus venosus flow demonstrated higher downstream impedance to filling, than in controls, suggesting altered compliance. The LUTO group also had lower distal descending aorta PI (1.53 ± 0.38 vs. 1.76 ± 0.44, P = 0.04), lower RIA-PI (1.31 ± 0.29 vs. 1.76 ± 0.44, P < 0.001) and lower LIA-PI (1.41 ± 0.44 vs. 1.73 ± 0.31, P < 0.01) than controls, suggesting vascular compression and increased impedance to flow.

CONCLUSIONS

LUTO with giant urinary bladder compresses the iliac arteries, which may lead to increased afterload. Further study is warranted to examine the impact of fetal treatment such as bladder drainage on these cardiovascular parameters.

Specific complications of monochorionic twin pregnancies: twin-twin transfusion syndrome and twin reversed arterial perfusion sequence

Monochorionic twins are subjected to specific complications which originate in either imbalance or abnormality of the single placenta serving two twins. This unequal placental sharing can cause complications including twin-twin transfusion syndrome (TTTS), twin anemia-polycythemia sequence (TAPS), selective intrauterine growth restriction or twin reversed arterial perfusion sequence (TRAP). Monochorionicity also makes the management of these specific complications as well as that of a severe malformation in one twin hazardous since the spontaneous death of one twin exposes the co-twin to a risk of exsanguination into the dead twin and its placenta. The latter is responsible for the death of the co-twin in up to 20% of the cases and in ischemic sequelae in about the same proportions in the survivors. Although the symptoms of all these complications are very different, the keystone of their management comes down to either surgical destruction of the inter-twin anastomoses on the chorionic plate when aiming at dual survival or selective and permanent occlusion of the cord of a severely affected twin aiming at protecting the normal co-twin. This can be best achieved by fetoscopic selective laser coagulation and bipolar forceps cord coagulation respectively.

Changes in umbilical venous volume flow after fetoscopic laser occlusion of placental vascular anastomoses in twin-to-twin transfusion syndrome

OBJECTIVE

To examine effects of fetoscopic laser occlusion of placental vascular anastomoses on umbilical venous volume flow in twin-to-twin transfusion syndrome.

STUDY DESIGN

Absolute umbilical venous volume flow, measured preoperatively and 48 hours after fetoscopic laser occlusion was related to Doppler studies, bladder filling in donors, and anastomoses.

RESULTS

Among 45 patients, recipients had decreased ductus venosus pulsatility index (ductus venosus-pulsatility index for veins, 1.16 vs 1.01; P < .001) and unchanged umbilical venous volume flow after fetoscopic laser occlusion (74.7 vs 74.5 mL; P = .407). Donors had decreased umbilical artery pulsatility (1.34 vs 1.11; P = .008), increased ductus venous-pulsatility index for veins (0.75 vs 0.91; P < .014), and significantly increased umbilical venous volume flow per kilogram by 52.3% (136.6 vs 208.0 mL/Kg/min; P < .001). Donor bladder filling occurred at higher umbilical venous volume flow per kilogram (142.7 vs 221.4 mL/Kg/min; P < .012). Increase in umbilical venous volume flow per kilogram correlated with the net difference in arteriovenous anastomoses (Pearson r = 0.403, P = .006).

CONCLUSION

Fetoscopic laser occlusion in twin-to-twin transfusion syndrome corrects intertwin differences in umbilical venous volume flow by predominant effects in the donor. Reappearance of donor bladder filling correlates with correction of volume flow.

The making of fetal surgery

Fetal diagnosis prompts the question for fetal therapy in highly selected cases. Some conditions are suitable for in utero surgical intervention. This paper reviews historically important steps in the development of fetal surgery. The first invasive fetal intervention in 1963 was an intra-uterine blood transfusion. It took another 20 years to understand the pathophysiology of other candidate fetal conditions and to develop safe anaesthetic and surgical techniques before the team at the University of California at San Francisco performed its first urinary diversion through hysterotomy. This procedure would be abandoned as renal and pulmonary function could be just as effectively salvaged by ultrasound-guided insertion of a bladder shunt. Fetoscopy is another method for direct access to the feto-placental unit. It was historically used for fetal visualisation to guide biopsies or for vascular access but was also abandoned following the introduction of high-resolution ultrasound. Miniaturisation revived fetoscopy in the 1990 s, since when it has been successfully used to operate on the placenta and umbilical cord. Today, it is also used in fetuses with congenital diaphragmatic hernia (CDH), in whom lung growth is triggered by percutaneous tracheal occlusion. It can also be used to diagnose and treat urinary obstruction. Many fetal interventions remain investigational but for a number of conditions randomised trials have established the role of in utero surgery, making fetal surgery a clinical reality in a number of fetal therapy programmes. The safety of fetal surgery is such that even non-lethal conditions, such as myelomeningocoele repair, are at this moment considered a potential indication. This, as well as fetal intervention for CDH, is currently being investigated in randomised trials.

Preoperative predictors of death in twin-to-twin transfusion syndrome treated with laser ablation of placental anastomoses

OBJECTIVE

To determine preoperative predictive factors for donor and recipient death after laser ablation of placental vessels in twin-to-twin transfusion syndrome.

STUDY DESIGN

Retrospective analysis of North American Fetal Therapy Network center laser procedures, 2002-2009. Factors associated with donor and recipient death were identified by regression analysis.

RESULTS

There were 466 patients from 8 centers. Factors significantly associated with donor fetal death were low donor estimated fetal weight (odds ratio [OR], 0.69; 95% confidence interval [CI], 0.55-0.87) and reversed end diastolic velocity in the umbilical artery (OR, 4.0; 95% CI, 1.54-10.2); for recipient fetal death-low recipient estimated fetal weight (OR, 0.65; 95% CI, 0.44-0.95), recipient reversed "a" wave in the ductus venosus (OR, 2.39; 95% CI, 1.27-4.51) and hydrops (OR, 3.7; 95% CI, 1.1-12.7); for recipient neonatal death-low donor estimated fetal weight (OR, 0.54; 95% CI, 0.30-0.95), high recipient estimated fetal weight (OR, 1.55; 95% CI, 1.06-2.26) and recipient reversed end diastolic velocity in the umbilical artery (OR, 7.8; 95% CI, 1.03-59.3).

CONCLUSION

Preoperative findings predict fetal and neonatal demise in twin-to-twin transfusion syndrome treated with laser therapy.

Improved recipient survival with maternal nifedipine in twin-twin transfusion syndrome complicated by TTTS cardiomyopathy undergoing selective fetoscopic laser photocoagulation

OBJECTIVE

The purpose of this study was to evaluate the effect of maternal nifedipine on fetal survival when started 24-48 hours before selective fetoscopic laser photocoagulation (SFLP).

STUDY DESIGN

We conducted a case control study of consecutive cases of twin-twin transfusion syndrome (TTTS) in which TTTS cardiomyopathy was treated with maternal nifedipine 24-48 hours before SFLP, compared with gestational age and stage-matched control cases. The primary outcome was recipient and donor survival.

RESULTS

One hundred forty-one cases of TTTS were treated with nifedipine, and 152 gestational age- and stage-matched control cases were analyzed. There was a significant increase in overall fetal survival in nifedipine-treated cases compared with control cases (237/284 [83%] vs 232/308 [75%]; P = .015). There is an increase in survival of recipients who were treated with nifedipine in stage IIIA (100% vs 81%; P = .021) and IIIB (93% vs 71%; P = .014); however, there was no difference in donor survival.

CONCLUSION

Maternal nifedipine is associated with improved recipient survival in TTTS that undergoes SFLP. This is the first study to suggest a benefit of adjunctive maternal medical therapy in patients with TTTS who undergo SFLP.

The Fetal Heart in Twin-to-Twin Transfusion Syndrome

Twin-to-twin transfusion syndrome is a severe complication occurring in 10% of monochorionic twin pregnancies. The disease is usually explained as due to an intrauterine imbalance in intertwin blood exchange, which leads to a volume depleted-donor twin and an overfilled recipient twin. The recipient has signs of cardiac dysfunction, which can be measured using echocardiography or blood and amniotic fluid derived biomarkers. Whereas cardiac dysfunction typically progresses in pregnancies treated with amniodrainage, it usually disappears within a few weeks after fetoscopic laser coagulation of the connecting intertwin anastomoses. Nevertheless, recipients remain at a increased risk of pulmonary stenosis. In this paper, we summarize the cardiac alterations in twin-to-twin transfusion syndrome, describe the changes seen after fetal therapy, list the newly proposed staging systems based on fetal cardiac function, and make recommendations about the use of fetal echocardiography in the evaluation and followup of pregnancies complicated by twin-to-twin transfusion syndrome.

Outcomes in a cohort of patients with Stage I twin-to-twin transfusion syndrome

OBJECTIVE

To determine pregnancy outcomes of patients who present with Stage I twin-to-twin transfusion syndrome (TTTS).

METHODS

This was a retrospective review of all patients with TTTS referred to our institution between January 2005 and December 2006. Quintero criteria were used for staging. Laser ablation was not offered to patients with Stage I disease.

RESULTS

A total of 155 twin pregnancies were evaluated for TTTS during this period. Forty-two met the criteria for Stage I and were included in the analysis. The overall survival to discharge was 82%. The mean gestational age at the time of consultation was 20.9 +/- 0.4 weeks. A total of 23 cases (54.8%) underwent amnioreduction. Progression of TTTS requiring invasive therapy occurred in four cases. The mean gestational age at delivery was 32.5 +/- 0.62 weeks. When divided according to use of amnioreduction, there were no statistically significant differences between the groups for gestational age at delivery or for birth weight. Those Stage I cases with a CHOP cardiovascular score of 5 or higher delivered almost 3 weeks earlier than the remainder of the cohort.

CONCLUSIONS

Progression of TTTS beyond Stage I occurred in only 9.5% of the cohort. Mean gestational age at delivery and survival to discharge did not differ between Stage I patients and those treated with placental laser ablation for more advanced stages of TTTS.

Evaluation of the CHOP cardiovascular score as a prognostic predictor of outcome in twin-twin transfusion syndrome after laser coagulation of placental vessels in a prospective cohort

OBJECTIVE

To investigate the prognostic value of cardiac function assessment by the previously reported CHOP (Children's Hospital of Philadelphia) cardiovascular score in twin-twin transfusion syndrome (TTTS).

METHODS

All consecutive monochorionic pregnancies presenting with TTTS over a 24-month period were evaluated by preoperative echocardiography before percutaneous laser coagulation of chorionic vessels. Each of the 12 items of the CHOP score was evaluated prospectively and the cardiovascular score was categorized into stages using previously published cut-offs. The outcome considered for this study was neonatal survival of neither, one or both twins.

RESULTS

In total, 215 pregnancies were enrolled. Due to technical issues, CHOP evaluation was incomplete in 16% of cases and follow-up was unavailable in 12%. Overall, there was a significant relationship between the CHOP score and the Quintero staging system, although this relationship was significantly reduced when parameters used in the Quintero system were removed from the CHOP score. Based upon neonatal survival, the CHOP score did not show any prognostic value regarding overall pregnancy outcome or individual recipient survival.

CONCLUSION

Cardiac function assessment using the CHOP score is not of clinical use as a prognostic marker in TTTS. This suggests that cardiac function may not be of interest for preoperative staging when laser coagulation is the first-line treatment, other than to confirm the diagnosis of TTTS requiring surgery.

Twin-twin transfusion syndrome: an ethics-based and evidence-based argument for clinical research

Aspects of twin-twin transfusion syndrome (TTTS) diagnosis, treatment alternatives, and research opportunities were considered during a consensus conference that was held by the North American Fetal Therapy Network in 2009. A 3-member scientific consensus panel gathered data from expert conference presentations, postconference communications, and comprehensive scientific literature database searches to develop recommendations for TTTS diagnosis, therapy, and research. The panel recommends retaining the Quintero staging system until a superior system has been validated appropriately. It concludes that there is normative equipoise to justify the performance of randomized clinical trials to identify the optimal treatment strategy for mild TTTS. Recommendations for the design and conduct of clinical trials and observational studies are also provided.

Fetal surgery is a clinical reality

An increasing number of fetal anomalies are being diagnosed prior to birth, some of them amenable to fetal surgical intervention. We discuss the current clinical status and recent advances in endoscopic and open surgical interventions. In Europe, fetoscopic interventions are widely embraced, whereas the uptake of open fetal surgery is much less. The indications for each access modality are different, hence they cannot substitute each other. Although the stage of technical experimentation is over, most interventions remain investigational. Today there is level I evidence that fetoscopic laser surgery for twin-to-twin transfusion syndrome is the preferred therapy, but this operation actually takes place on the placenta. In terms of surgery on the fetus, an increasingly frequent indication is severe congenital diaphragmatic hernia as well as myelomeningocele. Overall maternal safety is high, but rupture of the membranes and preterm delivery remain a problem. The increasing application of fetal surgery and its mediagenicity has triggered the interest to embark on fetal surgical therapy, although the complexity as well as the overall rare indications are a limitation to sufficient experience on an individual basis. We plead for increased exchange between high volume units and collaborative studies; there may also be a case for self-regulation. Inclusion of patients into trials whenever possible should be encouraged rather than building up casuistic experience.

Twin-to-twin transfusion syndrome: current understanding of pathophysiology, in-utero therapy and impact for future development

Whereas monochorionic twins account for only 30% of twin gestations, they contribute to a disproportionate extent to the overall twin perinatal morbidity and mortality. Twin-to-twin transfusion syndrome can occur at any point in a monochorionic gestation but is associated with significant increases in both morbidity and mortality when it develops before 26 weeks of gestation. It is still not possible to predict accurately those pregnancies that will be affected. This has resulted in the practice of routine ultrasound surveillance beginning at the end of the first trimester. Our understanding of the physiology still has many gaps but there is an increased recognition of the heterogeneity that exists especially in the early stages of the disease. The role of the cardiovascular response of the recipient twin offers the potential for further refining the application of our current treatment modalities and may offer insight into future therapies. The optimal therapy at this point in time resides clearly with selective laser photocoagulation, and further refinements of techniques and patient selection may continue to improve outcomes. Finally, the in-utero responses generated by the fetuses to the physiologic stress of twin-to-twin transfusion may influence their response or ability to respond to cardiovascular stress in later life. If there is in-utero programming, then the detection and timely treatment of conditions such as twin-twin transfusion syndrome may have lifelong implications for both members of the twin pair.

Profiling fetal cardiac function in twin-twin transfusion syndrome

OBJECTIVES

Cardiomyopathy in the recipient twin is a marker of severity in twin-twin transfusion syndrome (TTTS), making it a potentially valuable tool for staging the disease. This study aimed to provide a quantitative description of cardiac function in the recipient twin.

METHODS

Consecutive monochorionic pregnancies complicated with TTTS and treated by percutaneous laser coagulation underwent fetal echocardiography before surgery. An unsupervised classification analysis was conducted to identify groups of twins with similar cardiac profiles. The predictive value of the recipient twin's preoperative cardiac function based on these profiles was assessed, using perinatal death of at least one twin as the main outcome. The cardiac function profiles that we identified were compared with the current Quintero staging.

RESULTS

A total of 107 pregnancies were included, with six of these lost to follow-up; 63/107 complete cases were available for multivariate description of the recipient's cardiac function. Three different preoperative cardiac profiles were identified with increasing right and left myocardial performance index, decreasing right and left shortening fraction, and increasing ductus venosus pulsatility index. Although the three groups represented progressive stages of the syndrome-related cardiomyopathy, no correlation was found with pregnancy outcome. Of Quintero Stage 1 cases, 55% showed significant alterations of cardiac function in the recipient twin.

CONCLUSIONS

Progressive cardiomyopathy can be assessed quantitatively in the recipient twin and does not influence pregnancy outcome when fetoscopic laser coagulation is the first-line treatment. Compared with the current staging, cardiac profiling allows discrimination of cases with significant myocardial dysfunction.

Twin-to-twin transfusion syndrome: a comprehensive update

Twin-to-twin transfusion syndrome (TTTS) is a serious complication in about 10% to 20% of monozygous twin gestations with an incidence of 4% to 35% in the United States. Severe TTTS is reported to occur in 5.5% to 17.5% of cases. TTTS is a progressive disease in which sudden deteriorations in clinical status can occur, leading to death of a co-twin. Up to 30% of survivors may have abnormal neurodevelopment as a result of the combination of profound antenatal insult and the complications of severe prematurity. This article presents an overview of what is known about the pathophysiology and the diagnosis of TTTS, the role of echocardiography in TTTS, treatment options available for TTTS, complications of treatment for TTTS, and short- and long-term outcomes of TTTS.

The role of fetal echocardiography in fetal intervention: a symbiotic relationship

In this review, the authors explore the role of noninvasive and invasive fetal interventions in fetal cardiovascular disease guided by observations at fetal echocardiography. They first review fetal cardiac lesions that may be ameliorated by fetal intervention and then review noncardiac fetal pathologic findings for which fetal echocardiography can provide important insight into the pathophysiology and aid in patient selection for and timing of intervention and postintervention surveillance.

Assessment of fetal cardiac function before and after therapy for twin-to-twin transfusion syndrome

OBJECTIVE

We sought to assess fetal cardiac function in monochorionic twins before and after therapy for twin-to-twin transfusion syndrome (TTTS) and compare it with control subjects.

STUDY DESIGN

We conducted prospective longitudinal assessment of fetal cardiac function in cases undergoing curative fetal therapy for TTTS (n = 39) until 4 weeks postoperatively and in uncomplicated monochorionic twins (n = 23). Fetal cardiac function was assessed by the left and right ventricular myocardial performance index, atrioventricular valve flow pattern, ductus venosus a-wave, and umbilical vein pulsations.

RESULTS

Nomograms for the myocardial performance index were constructed. Fetal cardiac function was grossly abnormal in recipient twins of TTTS when compared with control subjects (P < .001 for all indices) but normalized by 4 weeks postoperatively. The donor developed abnormal ductus venosus flow and tricuspid regurgitation postoperatively that regressed within 4 weeks.

CONCLUSION

The cardiac dysfunction in the recipient twin of TTTS normalizes within 1 month after laser. The donor develops a transient impairment of cardiac function postoperatively.

Validation of the fetal myocardial performance index in the second and third trimesters of gestation

OBJECTIVES

To test the validity of the myocardial performance index (MPI) and its components against the more conventional methods of fetal cardiac function assessment: the ejection fraction (EF) for systolic function and the E/A index (ratio of transmitral flow during early (E) ventricular filling to flow during atrial (A) contraction) for diastolic function, both in a normal population and in a population at risk for cardiac failure because of volume overload (recipient fetuses in cases of twin-twin transfusion syndrome (TTTS)).

METHODS

The MPI was measured prospectively in addition to more commonly used indices of systolic (EF) and diastolic (E/A index) cardiac function in 117 healthy fetuses (gestational age range, 20-36 weeks) and in 14 fetuses suspected of cardiac failure because of the presence of TTTS. Nomograms were constructed for all variables, and correlations between the MPI, EF and E/A index were assessed. The time taken to obtain the measurements as well as the interobserver and intraobserver variability were determined for the MPI and EF.

RESULTS

In healthy fetuses, the MPI and EF were independent of gestational age, whereas the E/A index and isovolumetric relaxation time (IRT) increased with gestational age. The MPI correlated inversely with the EF (P<0.001). The IRT showed a trend towards an inverse correlation with the E/A index (P=0.10). The mean+/-SD time needed to measure the MPI and EF was 140+/-65 s and 185+/-187 s, respectively (P=0.43). Interobserver and intraobserver intraclass correlation coefficients for the MPI were 0.98 (95% CI, 0.85-0.99) and 0.82 (95% CI, 0.14-0.95), respectively; those for the EF were 0.58 (95% CI, -0.16 to 0.85) and 0.51 (95% CI, -0.46 to 0.83), respectively; and those for the E/A index were 0.97 (95% CI, 0.88-0.99) and 0.91 (95% CI, 0.66-0.98), respectively. All variables, except ejection time, were significantly different between normal fetuses and those with TTTS.

CONCLUSIONS

The MPI is an indicator of the systolic component of fetal left ventricular function that can be easily acquired and reproduced. The MPI is strongly correlated with the EF but shows less interobserver and intraobserver variability.